Prevent in-app web views from opening external URLs

[herzbube]

1. Open any one of the following in-app web views: About tab, Source Code tab, any one of the entries on the Licenses tab, Credits tab, any one of the entries on the Changelog tab.
2. Tap on a link.
3. Safari is launched and the external URL behind the link is opened.
4. Go back to the app.

Expected: The web view still shows the in-app content (e.g. the About document).

Actual: The web view has navigated away from the in-app content to the external URL. Because there is no way to navigate back the original in-app content is now inaccessible to the user until the app is launched the next time.